Central heating wont turn off

U

uroman

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I have just built a new house and got the central heating going(oil fired burner). However the heating keeps going even when the thermostat is turned away down. When I turn the thermostat up I can still hear the click but it is working regardless of what temperature is set. What could be causing the problem?
 
The thermostat does not turn off the burner. It turns off the water flow . Either the pump or in the case of zoned installations it closes the valve to the zone. This causes the water in the system to stop losing heat and after a time when the water heats to the boiler cut off temp the boiler will cut out. So if you mean the boiler does not cut out instantly this is normal. However if it does not cut out at all then the thermostat is not wired properly.
 
It does cut out at all which must mean it is not wired correctly. Is it a big job to get theis fixed?
 
No if you are at all handy with tracing wiring.

If its a simple system then everything may be wired back to the boiler. Check if there is a wiring diagram and if the thermostat connections have any wires connected also open the room thermostat and see if there are wires connected there. If so disconnect the wires at the boiler and with a multimeter check that a continuous loop exists when the stat is set to max and an open circuit exists when set to min. If that is ok then you can mimic the action of the thermostat at the boiler with a loop of wire. You should be able to narrow down the problem to either a faulty stat or wrong wiring and fix accordingly. Be careful as most domestic stats carry full mains voltage. if you have not worked with electricity before this is a bad place to start so get someone who has to do it for you. Simplest explanation is a loose wire at either end of the circuit .
 
HighFlier said:
The thermostat does not turn off the burner. It turns off the water flow . Either the pump or in the case of zoned installations it closes the valve to the zone. This causes the water in the system to stop losing heat and after a time when the water heats to the boiler cut off temp the boiler will cut out. So if you mean the boiler does not cut out instantly this is normal. However if it does not cut out at all then the thermostat is not wired properly.
Click to expand...

not correct
in a zoned installation there will be multiple stats. when any stat calls for heat a signal is sent to the panel which then switches on the boiler and powers an actuator to let hw into the zone and as long as any stat requires heat, the boiler and its pump stays switched on. the boiler stat regulates the water temp and kicks the burner in and out as required to maintain the set water temp through the boiler.

in a standard system the typically single room stat works as the op expected and if its switched off the boiler should be off as well.
boilers are supposed to (a lot dont) have a frost stat wired in which switches it on automatically in v. cold weather to protect the pipes from freezing. as thats independant from the room stat, maybe it is the issue
 
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